The present invention relates generally to improvements in apparatus for tracking a seam between two work members that are to be joined, such as by welding, and specifically to the provision of such tracking apparatus which is simpler in construction, which can be used on a greater variety of seams, which provides better tracking and which compensates for any tilting of the seam sensor.
Several apparatus for tracking seams have been provided heretofore, and suitable examples thereof are illustrated in the following U.S. Pat. Nos. 2,921,179 granted Jan. 12, 1960 to N. E. Anderson; 2,971,079 granted Feb. 7, 1961 to M. R. Sommeria; 3,017,496 granted Jan. 16, 1962 to W. J. Greene; 3,156,856 granted Nov. 10, 1964 to H. M. Nance, 3,171,071 granted Feb. 23, 1965 to R. L. Brown; 3,179,786 granted Apr. 20, 1965 to W. J. Greene; 3,201,562 granted Apr. 17, 1965 to N. E. Anderson; 3,359,486 granted Dec. 19, 1967 to D. R. Brosious, and 3,484,687 granted Dec. 16, 1969 to D. Wofsey. None of these prior patents shows the use of ferrite cores in a sensing head or the simplicity of construction of the present invention; the ferrite cores provide a better control signal for controlling the tracking apparatus.
Among the patents referred to, only the Wofsey U.S. Pat. No. 3,484,687 discloses apparatus for correcting the control signal to compensate for tilt of the primary sensors about an axis parallel to the seam on which the apparatus is operating. The present invention provides an improved and simplified tilt compensating circuit which is not found in any of the above listed prior art.